This invention relates generally to centrifugal pumps magnetically coupled to a rotary drive and more particularly to pumps having a sealing diaphragm between the driving magnets and the driven magnets.
Magnetic centrifugal pumps are utilized where an absolutely tight seal towards the outside is a concern since toxic, caustic or aggressive agents are to be pumped without leakage into the environment. A magnetic rotational coupler is provided in a magnetic centrifugal pump.
One particular type of magnetic coupler has inner and outer rotors including magnets disposed in mutually coaxial cylinders for magnetic coupling between the rotors. A separating diaphragm or containment shell is provided between the magnets of the inner and outer rotors. In this type of magnet coupler, the magnets are axially positioned. Most designs of magnetically coupled pumps use axially positioned magnets. A disadvantage with axially positioned magnets is that a pot shaped containment shell is required. This shell is expensive to manufacture and requires special tooling. The axial placement of the magnets makes the overall pump much longer axially. Axially positioned magnets also usually require two sets of product lubricated bearings.
The foregoing illustrates limitations known to exist in present magnetically coupled centrifugal pumps. Thus, it is apparent that is would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.